It is sometimes required that a trigger-operated electrical device, such as an electric power tool, be continuously operated for an extended period of time at a desired speed setting. To alleviate fatigue in the user's finger operating the trigger, a “lock-on” mechanism is provided to allow locking of the power tool at the desired speed of operation without the user having to maintain pressure on the trigger. The same lock-on mechanism may also be configured to serve a dual-function as a “lock-off” mechanism—that is, a mechanism that is selectably movable into a locked-off position in which the trigger is prevented from being squeezed and the electric device is prevented from being turned on. One perceived problem with such dual-purpose lock-on/lock-off mechanisms is that a user may become confused and inadvertently deactivate the lock-off mechanism and allow the electric device to turn on causing harm to the user.